EP1153060B1 - Method for producing poly-(1,4-phenylenazine-n,n-dioxide) by oxidising p-benzoquinonedioxime - Google Patents

Abstract

The invention relates to a method for producing poly(1,4-phenylenazine-N,N-dioxide) and derivatives thereof which are substituted in the ring, by oxidizing p-benzoquinonedioxime or the corresponding derivative thereof which is substituted in the ring, using polyanions of the halogens bromine or iodine. Tribromide Br3- or triiodide I3- can be used as polyanions and these can be obtained in situ from H2O2 and a bromide or iodide.

Description

The invention relates to a method for producing Poly- (1,4-phenylenazine-N, N-dioxide), which is also known as Is called poly-N, N-diaza dioxide, and its core-substituted derivatives by oxidation of p-benzoquinone dioxime, or its corresponding core-substituted derivatives, by means of polyanions of Halogens bromine or iodine.

Poly (1,4-phenylenazine-N, N-dioxide) is a highly effective Crosslinker in rubber mixtures or rubber-metal binders. In addition, the Use of this substance as recyclable Evaporation chemical for the production of electronic Circuits via laser inscriptions (Solventless Laser-Imageable Resist Process).

For the synthesis of poly (1,4-phenylenazine-N, N-dioxide) and In principle, its core-substituted derivatives only an oxidative route starting from p-benzoquinone dioxime or its core-substituted derivatives, because the reduction of the corresponding nitro compounds not stopped at the nitroso compound level can be. Examples of oxidants are Chlorine, nitrogen monoxide / sodium hypochlorite, Sodium chlorate, nitric acid, ferric chloride and Potassium hexacyanoferrate (III) known.

Primary reaction product of all of the above Oxidation reactions is a dinitroso compound. It is characteristic of almost all p-dinitroso compounds their spontaneous polymerization to poly-N, N-azodioxides. For example, p-dinitrosobenzene is -240 ° C Monomer and between -90 ° C and -50 ° C as a dimer, or Oligomer before. At higher temperatures (-10 ° C to 100 ° C) only poly (1,4-phenylenazine-N, N-dioxide) can be found.

A disadvantage of the previously known manufacturing processes is in most cases the resulting, sometimes enormous salt load. The following table gives examples of this: Salt load resulting from the oxidation of p-benzoquinone dioxime depending on the oxidizing agent used. oxidant Salt load per 100 kg poly-N, N-azodioxide K ₃ [Fe (CN) ₆ ] 510 kg complex salt FeCl ₃ 184 kg FeCl ₂ NO / NaOCl 85 kg NaCl NaClO ₃ / HCl 85 kg NaCl

Other methods are salt-free, but show for that other disadvantages. So is the oxidation by Nitric acid with yields <80% not very economical and by the need to make the reaction product effective having to wash, disadvantageous formation of Sewage.

The oxidation with elemental chlorine initially proceeds via the formation of hydrochloric acid free of salt, as does the oxidation in the H ₂ O ₂ / hydrochloric acid system. Elemental chlorine is released in situ from hydrochloric acid and hydrogen peroxide (Equation 1). The chlorine also serves as an oxidizing agent. 2 HCl + H ₂ O ₂ → Cl ₂ + 2 H ₂ O Cl ₂ + H ₂ O ₂ → 2Cl ^- + 2 H ⁺ + O ₂

The possible reaction of the chlorine formed with Hydrogen peroxide according to equation (2) can be used Release oxygen. A direct oxidation of p-benzoquinone dioximes with hydrogen peroxide, not observed even at elevated reaction temperature.

The mother liquor obtained must be used in these processes including any necessary wash water neutralized be, which in turn leads to the emergence of a salt load leads. Another disadvantage is that a more extensive Oxidation of the reaction product to p-dinitro compounds cannot be excluded. These connections are explosive and highly toxic.

In the context of mechanistic considerations, A. Ermakov and YF Komkova (Zh. Org. Khim. 20, 10, 2252 (1984), according to the oxidation with chlorine (from H ₂ O ₂ / hydrochloric acid), refer to the oxidation with in-situ iodine (from H ₂ O ₂ and potassium iodide) analogous to equation 1. However, a production process with iodine or iodine formed in situ is not described in this document.

The direct implementation of p-benzoquinone dioxime with elemental iodine (comparative example A) leads however in little uniform reaction only after a relatively long time Response times to the primary dinitroso product, that too can be obtained in low yield. Elemental iodine thus appears to be of little use Oxidizing agent for the technical oxidation of p-benzoquinone dioximes.

So far, there is no technical process the quantitative oxidation of p-benzoquinone dioximes to the corresponding poly-N, N-diazadioxiden under strictly avoiding the formation of toxic Dinitron by-products allowed and the one, also avoids indirect, salt load.

The object of the invention is therefore to overcome the disadvantages of To overcome the prior art and a method for Production of poly (1,4-phenylenazin-N, N-dioxide) and to create its core-substituted derivatives through a complete implementation of the reactants to the exclusion of the formation of dinitro derivatives, the Avoidance of salt loads and a clear one Reduction in the amount of waste water.

The object is achieved by that specified in claim 1 Procedure solved. Claims 2 to 12 form that Proceed further.

It has surprisingly been found that easily accessible derivatives of the halogens, namely the polyanions, lead to a significant increase in the chemoselectivity of the oxidation reactions described above. Polyanions (X _z ^- , z ≥ 3) of the halogens (X) are very easily accessible through the reaction of halide ions (X ^- ) with the elements, for example: X ₂ + X ^- → X ₃ ^-

Trihalides of chlorine, bromine and iodine form, as can be seen from the equilibrium constants according to Table 2 valid for the solvent water, increasingly easier with increasing atomic number. Equilibrium constants of trihalide formation in water (X ₂ + X ^- → X ₃ ^- ) K _chlorine = 0.01 K _bromine = 18 K _iod = 725

It is evident that a very large excess of chloride ions is necessary for the formation of trichloride ions (Cl ₃ ^- ). Experiments with increasing chloride ion concentration in the HCl / H ₂ O ₂ system actually lead to an increased chemoselectivity of the oxidation process.

If the oxidation at a given temperature in 15% Hydrochloric acid performed, the poly-N, N-diaza dioxide obtained with yields of 90 to 95% and contains approx. 1 % p-dinitrobenzene. An increase in concentration Hydrochloric acid to 25 or 35% leads with p-dinitrobenzene contents of only 6000 or 1200 ppm in End product to a significant reduction in By-product formation. The increased chemical However, selectivity is associated with a decrease in isolated yields connected to about 80%. The one with the Variation in the chloride ion concentration associated Changing the redox potential leads to one Loss of reactivity.

Due to the larger equilibrium constants (table 2) For the halogens bromine and iodine, the bromide or Iodide concentration should not be chosen to be as high as one to get greater selectivity. Therefore, only the bromine and iodine polyanions of more practical Significance for the method according to the invention, wherein mainly tribromide or triiodide is used. The oxidizing polyanions are at least stoichiometric amount and at most twice stoichiometric amount.

The tribromide or triiodide can advantageously be the appropriate alkali compound can be used.

An alkali metal tribromide from the group LiBr ₃ , NaBr ₃ KBr ₃ , RbBr ₃ and / or CsBr ₃ can be used as the tribromide. An alkali metal triiodide from the group LiI ₃ , NaI ₃ , kI ₃ , RbI ₃ and / or CsI ₃ can be used as the triiodide.

Instead of being added separately, the tribromide or triiodide can also be prepared in situ from a bromide or iodide compound and H ₂ O ₂ , the corresponding alkali compound advantageously being used.

The process can be carried out particularly advantageously if triiodide (I ₃ ^- ) is chosen as the oxidizing agent which is obtained in situ from an alkali iodide and H ₂ O ₂ . The alkali iodide can be used in a catalytic to stoichiometric amount of 0.1 to 100 mol%, based on the amount of p-benzoquinone dioxide. The primarily formed iodine spontaneously reacts to the alkali metal triiodide according to the equilibrium constants listed in Table 2. A violet color due to elemental iodine is therefore not observed. The reaction of the triiodide thus obtained with p-benzoquinone dioxime leads selectively to the formation of poly-N, N-diazadioxiden and iodide ions.

By controlled addition of further hydrogen peroxide The iodide released again becomes triiodide educated. A catalytic cycle arises, and it can LiI, NaI, KI, RbI or CsI also in small, so non-stoichiometric doses for synthesis be used. A preferred amount of the Alkali iodide is 1 to 5 mol%, based on the amount of p-benzoquinone dioxide used.

The amount of H ₂ O ₂ added is typically 100 to 110 mol%, based on p-benzoquinone dioxime.

A preferred process variant is typically carried out as follows: p-benzoquinone dioxime (or one of its nucleus-substituted derivatives) is slurried in water and 1 to 5 mol% of an alkali iodide are added. The well-stirred suspension is then mixed with 100 to 110 mol% H ₂ O ₂ (based on p-benzoquinone dioxime) in the form of a 30% hydrogen peroxide solution at a temperature selected between 10 and 65 ° C. in 2 to 4 hours. After the addition has ended, stirring is continued for a further 1 to 2 hours at a given temperature in order to complete the reaction. The yellow to light brown reaction product is filtered and washed with a little water. Mother liquor and filtrate are combined and can be used again for synthesis without further treatment, so that ideally no waste water is produced.

The method according to the invention is preferred for a pH of about 3 to 7 carried out. At this pH the process product forms poly- (1,4-phenylenazin-N, N-dioxide), or one of its core-substituted derivatives in very good yields as well filterable, crystalline precipitate. A lower pH will result tends to lead to poorer yields, a higher pH has the consequence that the product as bad filterable amorphous mass fails. pH-correction can e.g. with small amounts of alkali hydroxide such as NaOH or KOH, or e.g. with small amounts of mineral acids, such as HBr or HI can be made.

The poly (1,4-phenylenazine-N, N-dioxide) produced by the process according to the invention is free from p-dinitrobenzene. Even an excess of H ₂ O ₂ of 100% does not lead to the formation of dinitro derivatives. The process is therefore highly chemoselective.

The isolated yields in the preferred Triiodide oxidation processes are between 96 and 100%, which corresponds to a quantitative implementation.

The object of the invention will become apparent from the following Examples explained in more detail:

Comparative Example A: Oxidation of p-benzoquinone dioxime with elemental iodine (I ₂ )

27.6 g of p-benzoquinone dioxime were placed in a round bottom flask (CD) (0.20 mol) and 25.4 g iodine (0.10 mol) in 320 ml Water stirred at room temperature. After 2 days a sample taken and dried. The received one Solid was almost completely soluble in chloroform. The formation of poly- (1,4-phenylenazine-N, N-dioxide), which is very sparingly soluble in chloroform could do so largely be excluded. After a response time of the reaction mixture became a further 6 days Evaporated drying and then in chloroform added. After filtration and drying only 0.90 g of a brown-black solid be isolated. Among other products, the IR spectrum shows the presence of poly (1,4-phenylenazine-N, N-dioxide) on.

Examples 1 to 9: Oxidation of p-benzoquinone dioxime with triiodide I ₃ ^-

In Examples 1 to 9 was as follows General manufacturing procedure:

41.4 g of p-benzoquinone dioxime (CD) (0.30 mol) in 250 ml of water were placed in a 1 1 four-necked flask equipped with a KPG stirrer, dropping funnel, reflux condenser and internal thermometer, and a corresponding amount of alkali iodide (see Table 3) was added , 35.5 g of Perhydrol® (30% H ₂ O ₂ ) (0.31 mol H ₂ O ₂ ) were then added dropwise to this mixture over the course of 3 hours in such a way that the internal temperature of the reaction vessel was consistently between 20 and 40 ° C. was. Depending on the purity of the starting materials, the pH was between 2.6 and 5.5.

Then stirring was continued for 1 hour, then filtered off and washed with 50 ml of water. The yellow-brown solid obtained was then dried in a desiccator over P ₂ O ₅ to constant weight and identified by means of the IR spectrum. The yields of the poly- (1,4-phenylenazine-N, N-dioxide) obtained in each case are listed in Table 3. Alkali iodide and the amount used, as well as the yield of the poly- (1,4-phenylenazine-N, N-dioxide) obtained E.g. alkali iodide Amount of alkali iodide [g] / [mol%] on CD Yield [g] / [%] 1 Nal 2.25 / 5.00 40.7 / 99.7 2 KJ 0.50 / 1.00 38.7 / 94.8 3 KJ 1.25 / 2.50 39.8 / 97.5 4 KJ 2.50 / 5.00 39.7 / 97.2 5 CsI 1.95 / 2.50 39.8 / 97.5 6 CsI 3.90 / 5.00 39.9 / 97.8 7 KJ + CsJ 1.25 1.95 / 2.50 2.50 39.8 / 97.5 8th CsI 3.90 / 5.00 39.8 / 97.5 9 CsI 3.90 / 5.00 40.6 / 99.5

The IR spectrum showed the chemical in all cases Identity with a reference spectrum. p-dinitrobenzene could not be demonstrated in any case (GC, Chloroform extract against external standard). The products were all very easy to filter. They showed in Scanning electron microscope platelet-shaped and rod-shaped Crystals with an edge length of 0.5 to 5 µm (sporadically up to 40 µm), which generally become spherical Agglomerates of 10 to 20 µm were stored together.

Claims (12)

1. Process for the preparation of poly-(1,4-phenyleneazine N,N-dioxide) and its nuclearly substituted derivatives, by oxidation of p-benzoquinonedioxime or its corresponding nuclearly substitute derivatives, characterised in that the oxidation is carried out by means of polyanions of the halogens bromine or iodine (polyanions = X_z ^- wherein z ≥ 3 and X = Br or I).
2. Process according to claim 1, characterised in that a tribromide Br₃ ^- or triiodide I₃ ^- is used as the polyanion.
3. Process according to claim 2, characterised in that an alkali tribromide from the group LiBr₃, NaBr₃, KBr₃, RbBr₃ and/or CsBr₃ is used as the tribromide.
4. Process according to claim 2 or 3, characterised in that the tribromide is obtained in situ from the corresponding bromide Br^- and hydrogen peroxide H₂O₂.
5. Process according to claim 2, characterised in that an alkali triiodide from the group LiI₃, NaI₃, KI₃, RbI₃ and/or CsI₃ is used as the triiodide.
6. Process according to claim 2 or 5, characterised in that the triiodide is obtained in situ from the corresponding iodide I^- and hydrogen peroxide H₂O₂.
7. Process according to claim 6, characterised in that the iodide used is an alkali iodide in an amount of from 0.1 to 100 mol% relative to the p-benzoquinonedioxime or to a nuclearly substituted derivative thereof.
8. Process according to claim 7, characterised in that the alkali iodide is used in an amount of from 1 to 5 mol% relative to the p-benzoquinonedioxime or to a nuclearly substituted derivative thereof.
9. Process according to any one of claims 6 to 8, characterised in that the H₂O₂ is used in an amount of from 100 to 110 mol% relative to the p-benzoquinonedioxime or nuclearly substituted derivative thereof.
10. Process according to any one of claims 1 to 9, characterised in that the p-benzoquinonedioxime or a nuclearly substituted derivative thereof is suspended in water prior to the oxidation.
11. Process according to any one of claims 1 to 10, characterised in that the reaction temperature is from 10 to 65°C.
12. Process according to any one of claims 1 to 11, characterised in that the reaction is carried out at a pH value from 3 to 7.